This invention relates to a power steering fluid system for an automobile vehicle, and particularly to a fluid reservoir for a power steering fluid system. The reservoir incorporates a filtration unit that is functionally located in the fluid return line from the power steering unit to the fluid pump that supplies pressurized fluid to the power steering unit.
A typical power steering system for a motor vehicle includes a fluid pump for supplying pressurized fluid to a power steering unit that is connected to a return line that leads back to the pump. Often the fluid system includes a filter for trapping solid contaminants that can form during prolonged usage of the power steering system. The filter can be located in the pressure line between the pump and steering unit, or in the return line between the steering unit and the pump. In many non-sealed systems a reservoir is provided for supplying steering fluid to the system, and for accommodating excess fluid volumes associated with high fluid temperatures that occur in high temperature environments and/or cyclic operation of the power steering unit.
The present invention relates to a fluid reservoir for power steering fluid, wherein the reservoir, which incorporates a filter, is functionally located in the return line between the power steering unit and the fluid pump. The reservoir is designed so that the fluid flowing through the filter is in a swirling condition, whereby heated fluid is mixed with relatively cool fluid so as to achieve a reasonably even fluid temperature, without hot spots as might degrade the fluid or cause fluid foaming.
A particular aim of the invention is to provide a reservoir having a relatively small height dimension, whereby the reservoir can fit within small spaces in the vehicle engine compartment. Typically, the reservoir height dimension can be in the neighborhood of six inches.
Patents of prior art interest are U.S. Pat. No. 5,906,221 to M. Mancell, U.S Pat. No. 5,820,356 to D. Ogbuaku, U.S. Pat. No. 4,650,572 to W. Hayes, and U.S. Pat. No. 5,918,760 to S. Frodin. The fluid reservoir of the present invention is advantageous over the prior art as regards compactness, good fluid mixing cavitation prevention, and low noise production. Circumferential swirling motion of the fluid is controlled to prevent cavitation of the swirling fluid mass, as might produce undesired noise. The filter is designed to exert a back pressure in the fluid return line, so as to minimize pulsations or flow variations that might generate a perceptible shudder or vibration during operation of power steering unit.
Further features of the invention will be apparent from the attached drawings and description of an illustrative embodiment of the invention.